Girls simultaneously shout "DUH!"

Orgasms: a real ‘turn-off’ for women

17:54 20 June 2005
NewScientist.com news service
Michael Le Page, Copenhagen

For women, it seems, sex is a big turn-off, reveals a brain scanning study. It shows that many areas of the brain switch off during the female orgasm - including those involved with emotion.

“At the moment of orgasm, women do not have any emotional feelings,” says Gert Holstege of the University of Groningen in the Netherlands.

His team recruited 13 healthy heterosexual women and their partners. The women were asked to lie with their heads in a PET scanner while the team compared their brain activity in four states: simply resting, faking an orgasm, having their clitoris stimulated by their partner’s fingers, and clitoral stimulation to the point of orgasm.

The results of the study are striking. As the women were stimulated, activity rose in one sensory part of the brain, called the primary somatosensory cortex, but fell in the amygdala and hippocampus, areas involved in alertness and anxiety. During orgasm, activity fell in many more areas of the brain, including the prefrontal cortex, compared with the resting state, Holstege told a meeting of the European Society for Human Reproduction and Development in Copenhagen on Monday.

In one sense the findings appear to confirm what is already known, that women cannot enjoy sex unless they are relaxed and free from worries and distractions. "Fear and anxiety levels have to go down for orgasm. Everyone knows this but we can see it happening in the brain," he explains.

Extraordinary behaviour

From an evolutionary point of view, it could be that the brain switches off the emotions during sex because at such times the chance to produce offspring becomes more important than the survival risk to the individual. Holstege points to the extraordinary behaviour seen in some animals during the breeding season, such as March hares, when the urge to mate seems to override the usual fear of predators.

But Holstege cannot explain why there is such extreme deactivation in so many areas of the brain during orgasm. Only one small part of the brain, in the cerebellum, was more active during female orgasm. The cerebellum is normally associated with coordinating movement, though there is also some evidence that it helps regulate emotions. “We don’t know what activation of the cerebellum corresponds to,” Holstege admits.

His study also revealed clear differences when women were faking an orgasm. Part of the brain involved controlling conscious movement lit up, and there was none of the extreme deactivation.

Next the team hope to look at what happens to the brain in the minutes after orgasm, as well as in patients with sexual problems. The team has already done a similar study involving 11 men, which revealed far less deactivation during orgasm than in women. However, Holstege says the results are probably unreliable and need to be repeated. The problem is that PET scanners measure activity over two minutes - and in men it is all over in a few seconds.